Many industrial processes and machines are controlled and/or powered by electric motors. Such processes and machines include pumps providing fluid transport for chemical and other processes, fans, conveyor systems, compressors, gear boxes, motion control devices, screw pumps, and mixers, as well as hydraulic and pneumatic machines driven by motors. Such motors are combined with other system components, such as valves, pumps, furnaces, heaters, chillers, conveyor rollers, fans, compressors, gearboxes, and the like, as well as with appropriate motor drives, to form industrial machines and actuators. For example, an electric motor may be combined with a motor drive providing variable electrical power to the motor, as well as with a pump, whereby the motor rotates the pump shaft to create a controllable pumping system.
The components parts used to build such motorized systems (e.g., pumps, motors, motor drives, etc.) are commonly chosen according to specifications for a particular application in which the motorized system is to be employed. For instance, a set of specifications for a motorized pumping system may include flow rates or pressures or ranges thereof, which the system must accommodate for use in a particular application. In such a case, the pump is chosen according to the maximum and minimum flow and head required in the application, and the motor is selected based on the chosen pump. The corresponding motor drive is selected according to the motor specifications. Other pumping system components may then be selected according to the chosen motor, pump, and motor drive, which may include motor speed sensors, pressure sensors, flow sensors, and the like.
Such system design specifications are typically driven by maximum operating conditions, such as the maximum flow rate the pumping system is to achieve, which in turn drives the specifications for the component parts. For instance, the motor may be selected according to the ability to provide the necessary shaft speed and torque for the pump to achieve the maximum flow rate. Thus, the typical motorized system comprises components rated according to maximum operational performance. However, the system may seldom, if ever, be operated at these levels. For example, a pump system rated to achieve a maximum flow rate of 100 gallons per minute (GPM) may be operated at a much lower flow rate for the majority of its operation life.
In facilities where such motorized systems are employed, other operational performances characteristics may be of interest, apart from the rated output of the motorized system. For instance, the cost of operating a pumping system is commonly of interest in a manufacturing facility employing the system. The component parts of such a pumping system typically include performance ratings or curves relating to the efficiency of the component parts at various operating conditions. The energy efficiency, for example, may be a measure of the transferred power of the component device, which may be expressed as a percentage of the ratio of output power (e.g., power delivered by the device) to input power (e.g., power consumed by the device). These performance curves typically include one or more operating points at which the component operates at maximum efficiency. In addition to the optimal efficiency operating point, the components may have other operating points at which other performance characteristics are optimal, such as expected lifetime, mean time between failures (MTBF), audible noise or vibration output, time between expected servicing, safety, pollution emissions, or the like.
While the operating specifications for the components in a motorized (e.g., pumping) system may provide for component device selection to achieve one or more system operational maxima (e.g., maximum flow rate for a pumping system), other performance metrics (e.g., efficiency, cost, lifetime, MTBF, etc.) for the components and/or the system of which they form a part, are not typically optimal at the actual operating conditions. Thus, even where the efficiency ratings for a pump, motor, and motor drive in a motorized pumping system provide for maximum efficiency at or near the maximum flow rate specified for the pumping system, the efficiency of one or more of these components (e.g., as well as that of the pumping system overall) may be relatively poor for other flow rates at which the system may operate for the majority of the service life thereof. Thus, there is a need for methods and systems by which efficiency and other performance characteristics associated with motorized systems and components thereof may be improved.